A176638 - OEIS

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A176638

Partial sums of A018190.

1, 2, 5, 12, 34, 115, 446, 1881, 8386, 38472, 179701, 849285, 4047541, 19415118, 93623028, 453486806, 2205081449, 10758731196, 52651373968, 258365785954, 1270930958357, 6265738653554, 30952863554094, 153191072337297

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OFFSET

1,2

COMMENTS

Partial sums of number of planar simply-connected polyhexes (or benzenoid hydrocarbons) with n hexagons. The only known primes in the partial sum are 2 and 5.

LINKS

Table of n, a(n) for n=1..24.

FORMULA

a(n) = SUM[i=1..n] A018190(i).

EXAMPLE

a(6) = 1 + 1 + 3 + 7 + 22 + 81 = 115.

CROSSREFS

Cf. A000228, A002216, A018190, A038142-A038147.

Sequence in context: A151408 A121956 A348102 * A131467 A000103 A101292

Adjacent sequences: A176635 A176636 A176637 * A176639 A176640 A176641

KEYWORD

nonn

AUTHOR

Jonathan Vos Post, Apr 22 2010

STATUS

approved